Injection system for internal combustion engines, sensitive to the specific weight of the air



Apnl 4, 1967 G. GARCEA 3,312,208

INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES, SENSITIVE TO THE SPECIFIC WEIGHT OF THE AIR Filed Nov. 5, 1964 United States Patent ()fiice 3,312,208 Patented Apr. 4, 1967 3,312,208 INJECTION SYSTEM FOR INTERNAL COMBUS- TION ENGINES, SENSITIVE TO THE SPECIFIC WEIGHT OF THE AIR Giampaolo Garcea, Milan, Italy, assignor to Alfa Romeo-S.p.A., a company of Italy Filed Nov. 5, 1964, Ser. No. 409,208 Claims priority, application Mexico, Nov. 28, 1963, 24,258, Patent 715,699 4 Claims. (Cl. 123-140) The object of the present invention is an arrangement for injecting fuel into internal combustion engines, which is sensitive to the specific weight of the air and which allows the adjustment in an extremely simple manner of the input of fuel into the cylinders of the engine in accordance with the number of revolutions of said engine, the grade of atomization through the throttling valve and the specific weight of the ambient air.

It is a well-known fact that the means for injecting fuel into internal combustion engines include chiefly a pump feeding fuel under pressure into the different cylinders and a regulator associated with the actual pump. The injection pump is always provided with an arrangement for adjusting the amount of injected fuel and the regulator acts on said arrangement so as to measure automatically the amount of fuel fed so that said amount may always correspond to the weight of air aspirated by the internal combustion engine for all conditions of speed of rotation and for all the loads driven by the actual engine.

When controlling said pump arrangement, the operation of the regulator must therefore take into account not only the number of revolutions of the internal combustion engine and the grade of atomization through the throttle valve or else of the drop in pressure of the air across said throttle valve, but also the specific weight of the ambient air and consequently of the two parameters defining said specific weight, to wit: atmospheric pressure and ambient temperature. If, as generally occurs, the regulator acts on the position of a lever or a rod associated with said arrangement, and if the delivery of fuel is proportional to the movements thus imparted to said lever or rod, the adjustment of said movements with a view to matching the delivery of fuel with the particular values of the specific weight of the air aspirated should be performed, taking into account the fact that the feed of fuel and consequently the movements of said lever or rod must always be proportional to the specific weight of the air, all other conditions remaining the same. Consequently, the element taking into account the modifications in the specific weight of the air should be inserted mechanically in the kinematic chain extending between the actual regulator and the rod or lever of said adjusting arrangement with a view to obtaining said proportionality.

The difficulty of mechanically inserting said element is that the control rod or lever of the adjusting arrangement requires for each shifting the application of a certain force, not only due to mechanical friction, but also because it is generally provided with a somewhat resistant counter spring which serves for removing permanently all the clearances in the kinematic chain for obtaining the desired accuracy of adjustment. Obviously, any modifications in the specific weight of the air which make it necessary to ensure a corresponding shifting of the lever or rod, require a slight mechanical work by the elements sensitive to the modifications in the ambient pressure and temperature.

Said elements and, in particular, the element sensitive to the ambient pressure can supply only with difficulty a suflicient accuracy in the movements executed by the above mentioned forces unless the actual elements are of an exaggerated size and an intricate auxiliary mechanism is resorted to. It is also obvious that, since such a compensating element must be inserted in the kinematic chain so as to modify the position of the rod or lever in accordance with the modifications in the specific weight of atmospheric air, the movements of the kinematic parts of the actual regulator under the action of modifications in the number of revolutions or in the load of the engine, produce modifications in the load of the compensating element which is therefore subjected to deformations unless it is provided with a high rigidity. The object of the present invention is for protecting the compensating element against loads and deformations to which it may be subjected as disclosed. In order to solve the problem, the particular means in use with internal combustion engines for automobile applications will first be investigated and associated with the modifications in the specific weight of the air being traceable to pressure and temperature. Since the atmospheric conditions of the area in which the Vehicle operates change slowly or the vehicle is transferred from one area into another wherein the atmospheric conditions are different from those in the first area and vary very slowly, it is possible to ensure the compound adjustment no longer continuously but intermittently. This is the case when special kinematic and mechanical conditions governing the lever system connecting the actual regulator with the pump-controlling lever or rod are favorable for the insertion of the compensating element without opposing, under said particularly favorable conditions any forces against the action of the compensating element. It is thus possible to reach in the execution of the compensating elements advantages of a reduced weight, simplicity, small bulk and low cost price.

It may of course occur and this constitutes another object of the present invention, that the new kinematic structure associated with the insertion of the compensating element is not modified under the action of the loads appearing for all other conditions of operation different from the particularly favorable above mentioned conditions. As soon as said load appears, the particular structure of the mechanism is such that the movements of the compensating element are prevented and the loads referred to hereinabove do not reach by any means said compensating element.

A further object of the invention is that for which the special favorable conditions referred to hereinabove are obtained upon complete release of the accelerator pedal, or stoppage of the engine or operation of the engine. With the vehicle at a stands-till, in the case of modifications in the conditions governing the ambient atmosphere,

the compensating element acts continuously. When the vehicle is moving between two areas subject to different atmospheric conditions, which occurs chiefly in the case of a long ascent or long descent, the accelerator pedal is set at a sufiiciently high rhythm into its released position, such as upon change of speed for negotiating curves or slowing down and, whenever the pedal is thus released, the compensating element may act to modify the kinematic system connecting the actual regulator with the lever controlling the injection pump. If one takes into account the fact that the modifications in the proportions of the mixture corresponding to the modifications in the ambient conditions lie always within comparatively short ranges, it will be readily understood that a compensation of the abovfe'r'nentioned kind may be considered as perfelctjsincethejmeans ensuring compensation are simple, of a reduced weight and bulk and of a low cost price.

According to the present invention, there is provided an injection system for internal combustion engines, which is sensitive to the specific weight of the air and includes a regulator connected kinematically with a member adjusting the input of fuel fed by a pump into the engine cylinders so as to match the input with the various loads and speeds of revolution of the engine while a compensating element adjusts said input according to external atmospheric conditions and suitably modify said kinematic connection. According to the invention, said kinematic chain or connection is executed in a manner such that it is entirely cut out for particular conditions of operation of the engine so as to subject the actual kinematic chain to the compensating element without any straining, with a further modification outside said particular conditions of operation being prevented by the presence of suitable mechanical stops.

To allow an easier understanding of the operation and features of the arrangement according to the invention, a disclosure will now be given, by way of a non-limiting example, of a preferred embodiment of said invention, reference being made to the accompanying drawings of which the single figure illustrates a side view partly in section and partly in elevation of an engine according to the invention.

As shown, the actual injecting pump illustrated at 1 is adjusted to feed a four cylinder engine. The gasoline is supplied into the injectors of the different cylinders through connections 2 and small tubes 3, in registry with four pumping elements 4 within the pump. The lower ends of the pumping elements are controlled by push members 5 driven by a cam or eccentric member 6 rigid with a camshaft 7 driven by the engine, with a speed reduction equal to 1:2 in the case of four-stroke engines, through its splined end 8 registering with the flange means securing the pump to the engine. The adjustment of the amount of fuel thus injected so as to correspond with the requirements of operation of the engine is obtained since each pumping element 4 is provided with a helical groove, which is not illustrated, whereby a rotation of the pumping element about its axis modifies the length of the useful fuel-feeding stroke of the element. More specifically, the helical groove registers at an adjustable moment with the admission bore feeding fuel into the sleeve inside which the pumping element is angularly shifted. This method for obtaining an adjustment of the amount of fuel is well-known and conventional in the art. The application of other means instead of that briefly described is outside the scope of the present invention. In the embodiment illustrated, the rotation of the pumping element 4 is obtained because it is rigid with a partly toothed drum 9 meshing with a rack-shaped rod 10. The arrangement adjusting the amount 'of fuel is controlled by causing the rack 10 to move along its axis through actuation of a stud 11 secured to the inner end of the rack.

The automatic regulator controlling the rod or rack 10- and, consequently, the means adjusting the amount of fuel injected is constituted by a mechanism enclosed within body 12 secured through flanges to the body of the pump 1. In the particular case illustrated, the regulator is of a mechanical type constituted chiefly by a drum 13 having its outer surface forming a projecting cam 42. The position of said drum may be adjusted in two ways. First it may be shifted along its axis which registers with that of the camshaft 7 and second it may also rotate round said axis. The position assumed by the drum when it moves along its axis is defined by a centrifugal regulator controlled by the number of revolutions of the engine, so that for each engine speed, a different longitudinal position of the drum is obtained. In the particular case where the centrifugal regulator is a ball regulator, balls 14 are driven into rotation by blades 15 rigid with a disc 16 keyed to end 17 of the camshaft 7. The balls are held peripherally by a suitable bell-shaped member 18. Inside said bell-shaped member, the balls assume a position such that the component of the reaction parallel with the axis of rotation, in registry with the inner surface of the bell-shaped member, balances the elastic reaction of a spring 19 acting on the disc 16 through the drum 13 and a thrust bearing 20. The angular position of the drum during its rotary movement about its axis is defined in contradistinction by the position of a rod 21 adapted to slide in a suitable bore formed in the drum 13. The rod 21 is rigid with a lever 22 keyed to a spindle 23. A crank 24 is keyed to the outer end of the spindle. The angular setting of the crank corresponds kinematically through a terminal stud 25 with the angular position of the throttle valve atomizing the air aspirated by the engine and also the angular position of the lever controlled by the accelerator pedal. The connecting means, throttle valve and accelerator pedal are not illustrated since they are of conventional type.

The outer surface of the cam 42 is caused to engage a ball-shaped end 26 of a feeler 27 constituted by a lever pivoting at 28 and rigid with a further lever 29.

The angular movements of the lever 29 produce through an adjustable stop 30 a substantially longitudinal shifting of a rod 31 which in turn causes lever 32 to turn about its fulcrum 33. The free end of the lever 32 engages the stud 11 in such a manner that the pivotal movement of the lever 32 produces a longitudinal shifting of the rack 10, the position of which governs, as already mentioned, the amount of injected fuel. For each operative condition of the engine which depends for the same specific weight of the air on the angle assumed by the throttle valve and the rotary speed of the engine, the ball-shaped end 26 of the feeler 27 engages a corresponding well-defined point of the surface of the projecting cam 42. The radial values defining said cam surface are naturally designed so as to lead to positions of the feeler and, through the kinematic chain described, to positions of the rack such that the amount of injected fuel is always that required by the engine for the prevailing conditions of operation. If the specific weight of the air changes, such as changes in altitude or climate, it is obvious that the amount of injected fuel should change proportionally with said specific weight for an unvarying position of the throttle valve and an unvarying speed of revolution of the engine. To this end, the distance between the axis of the stop 30 and the pivot 28 is adjusted so as to be always proportional to said specific weight of the air. In the case illustrated, only the adjustment required by the modifications in the specific weight of the air traceable to modifications in external pressure is shown, since in practice the modifications in specific weight traceable to modifications in external temperature are of a lesser importance than those respecting external pressure and may therefore be overlooked. The adjustment of the position of the stop 30 with reference to the pivot 28 and thus the adjustment of the lever arms controlling the rod 31 is obtained through a barometric capsule 34 of a type well-known per se, the upper end of which is secured to the body of the regulator through a pivot 35 rigid with adjusting means. The lower end of the capsule may constrain the rod 31 to rock about the pivot 38 connecting it with the lever 32 through depression of its fulcrum 37.

Due to corrugations on the surface of the lever 29 in registry with the stop 30 engaging said corrugations or notches, the capsule 34, by reason of the reduced stresses such a capsule can exert, cannot cause the rod 31 to rotate about its pivot 38 unless an even, small clearance exists between the stop 30 and the lever 29 and the coupling is released between said stop 30 and lever 27. This latter condition is satisfied only when the engine is at a standstill or at least the throttle valve is closed and the engine disengaged whereby the thrust of spring 39 urging the rack-shaped rod 10 into its position corresponding to zero output is absorbed no longer through the stop 30 and the lever 29 but through projection 40 rigid with the rack 10 and stop 41 secured to the body of the regulator. The compensation of the modifications in the specific weight of the air is provided in anintermittent non-continuous manner, but in a satisfactory manner as concerns the operative requirements. The structure illus trated is a guarantee against the risk whereby under cer tain conditions a fraction of the thrust required for shifting the rack may be applied axially to the lower end of the capsule 34 and thus lead to undesirable deformations which would be extremely objectionable for engineregulating purposes.

This invention is not to be confined to any strict conformity to the showings in the drawings but changes or modifications may be made therein so long as such changes or modifications mark no material departure from the spirit and scope of the appended claims.

I claim:

1. A fuel injecting system for an internal combustion engine comprising an injection pump, means for adjusting the charges of fuel fed by the pump into the engine, a regulator responsive to the load and speed conditions of the engine, a kinematic chain operably connecting the regulator with the adjusting means and having at least two members, an adjustable connection between said members having a plurality of indexed positions each of which changes the degree of displacement transmitted to said adjusting means for a given response of said regulator, a compensating means sensitive to modifications in the specific weight of the ambient air, means for connecting said compensating means with one of said kinematic chain members tending to change the indexed position of said adjustable connection in accordance with said modifications, means on one of said kinematic chain members and spaced means on the other of said kinematic chain members connecting said members for maintaining an indexed position between said members during one range of load and speed conditions for said engine and releasing said members for relative change of the indexed position in accordance with change sensed by said compensating means in another range of load and speed conditions of the engine.

2. A fuel injecting system for an internal combustion engine comprising an injection pump, means adjusting the charges of fuel fed by the pump into the engine, a regulator responsive to the load and speed conditions of the engine, a kinematic chain operably connecting the regulator with the adjusting means and including a lever member controlled by said regulator and a rod member controlled by said lever member, an adjustable connection between said members having a plurality of indexed positions each of which changes the degree of displacement transmitted to said adjusting means fora given response of said regulator, a compensating means sensitive to the modifications in the specific weight of the ambient air, means connecting said compensating means with the rod member of the kinematic chain tending to change the indexed position of said adjustable connection in accordance with said modifications, said rod member and lever member controlled by the regulator being connected by means on one of said members and spaced means on the other of said members for maintaining an indexed position between said members during one range of load and speed conditions for said engine and releasing said members for relative change of the indexed position in accordance with a change sensed by said compensating means in another range of load and speed conditions of the engine.

3. A fuel injecting system for an internal combustion engine comprising an injecting pump, means adjusting the charges of fuel fed by the pump into the engine, a regulator responsive to the load and speed conditions of the engine, a kinematic chain operably connecting the regulator with the adjusting means and including a lever member controlled by said regulator and a rod member controlled by said lever member, an adjustable connection between said members having a plurality of indexed positions each of which changes the degree of displacement transmitted to said adjusting means for a given response of said regulator, a compensating means sensitive to the modifications in the specific weight of the ambient air, means connecting said compensating means with the rod member of the kinematic chain tending to change the indexed position of said adjustable connection in accordance with said modifications, said rod member and said lever member controlled by the regulator being connected by means on one of said members and spaced means on the other of said members for maintaining an indexed position between said members during one range of load and speed conditions for said engine and releasing said members for relative change of the indexed position in accordance with a change sensed by said compensating means in another range of load and speed conditions of the engine, said first-mentioned means including a corrugated section on one of said members and said secondmentioned means including a toothed section on the other member engaging said corrugated section.

4. A fuel injecting system for an internal combustion engine comprising an injection pump, means adjusting the charges of fuel fed by the pump into the engine, a regulator responsive to the load and speed conditions of the engine, a kinematic chain operably connecting the regulator with the adjusting means and having at least two members, an adjustable connection between said members having a plurality of indexed positions each of which changes the degree of displacement transmitted to said adjusting means for a given response of said regulator, a compensating means sensitive to the modifications in the specific weight of the ambient air, means connecting said compensating means with one of said kinematic chain members tending to change the indexed position of said adjustable connection in accordance with said modifications, means on one of said kinematic chain members and spaced means on the other of said kinematic chain members connecting said members for maintaining an indexed position between said members during one range of load and speed conditions for said engine and releasing said members for relative change of the indexed position in accordance with change sensed by said compensating means in another range of load and speed conditions of the engine, spring means acting on the kinematic chain to urge said chain into the position corresponding to zero throughput conditions for the pump, and an adjustable stop defining the end of the travel of the adjusting means to stop the adjusting means in a position corresponding approximately to said zero throughput conditions and absorb the thrust of the spring means.

References Cited by the Examiner UNITED STATES PATENTS 3,146,770 10/1964 Garcia 123140.31

FOREIGN PATENTS 811,904 4/1959 Great Britain.

MARK NEWMAN, Primary Examiner.

LAURENCE M. GOODRIDGE, Examiner. 

1. A FUEL INJECTING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING AN INJECTION PUMP, MEANS FOR ADJUSTING THE CHARGES OF FUEL FED BY THE PUMP INTO THE ENGINE, A REGULATOR RESPONSIVE TO THE LOAD AND SPEED CONDITIONS OF THE ENGINE, A KINEMATIC CHAIN OPERABLY CONNECTING THE REGULATOR WITH THE ADJUSTING MEANS AND HAVING AT LEAST TWO MEMBERS, AN ADJUSTABLE CONNECTION BETWEEN SAID MEMBERS HAVING A PLURALITY OF INDEXED POSITIONS EACH OF WHICH CHANGES THE DEGREE OF DISPLACEMENT TRANSMITTED TO SAID ADJUSTING MEANS FOR A GIVEN RESPONSE OF SAID REGULATOR, A COMPENSATING MEANS SENSITIVE TO MODIFICATIONS IN THE SPECIFIC WEIGHT OF THE AMBIENT AIR, MEANS FOR CONNECTING SAID COMPENSATING MEANS WITH ONE OF SAID KINEMATIC CHAIN MEMBERS TENDING TO CHANGE THE INDEXED POSITION OF SAID ADJUSTABLE CONNECTION IN ACCORDANCE WITH SAID MODIFICATIONS, MEANS ON ONE OF SAID KINEMATIC CHAIN 